This renewal proposal describes plans to continue a vigorous chemistry-biology interface (CBI) predoctoral training program that is designed to provide trainees with a core background in chemistry and cross-training in biological sciences. The program, which has been continuously funded by NIH since 1996, also promotes interdisciplinary collaborative research across the Cornell Campus. Each trainee will carry out his or her doctoral thesis research with one or more of 25 faculty trainers affiliated with eight participating units: Chemistry and Chemical Biology, Biomedical Sciences, Chemical and Biomolecular Engineering, Microbiology and Immunology, Molecular Biology and Genetics, Plant Biology, Plant Pathology, and Nutritional Sciences. Participating faculty have well-funded research programs in chemistry with strong connections to biology or vice versa. Students undergo training in areas that are broadly distributed over chemistry (synthetic organic, bioorganic, bioinorganic, biophysical, natural products, X-ray crystallography, metabolomics, and proteomics) and biology (protein structure and function, enzymology, immunology, signal transduction, chemotaxis, cell biology, host/pathogen interactions, and genomics). The CBI continues to successfully merge the cultures of chemistry and biology with effective didactic and programmatic initiatives. CBI trainees take a core set of rigorous courses in both chemistry and biology and undergo responsible conduct of research training. Trainees attend seminars in their core disciplines (usually weekly), participate together with faculty in a special monthly CBI seminar program, and organize monthly CBI Lit Lunches and an annual CBI symposium that features both internal and outside speakers. Two additional features distinguish the Cornell CBI program: First, each semester trainees invite, organize, and host special seminar speakers working at the interface of chemistry and biology. Secondly, trainees intern at a laboratory distinct from that of their thesis research, usually in the context of a biotech, life science, or pharmaceutical company. Through this experience they gain experience with interdisciplinary biomedical research and are exposed to non-academic careers. Several trainees have received employment offers after their internships. The program continues to produce a high-caliber cohort of trainees, who are increasingly more diverse in their backgrounds due to our continued and intensified recruitment of students from underrepresented groups. Importantly, CBI training has been achieved without affecting the time required to complete a PhD degree at Cornell. In this renewal the impact of the CBI will be increased by expanding its scope. Cornell so values the contributions of the CBI to training the next generation of scientists and in promoting collaborative research across campus that it has dramatically increased institutional support for the program, which includes the provision of up to five matching slots to expand trainee base. In addition, the CBI training activities will now become accessible to students who are not financially supported by the CBI program. These enhancements will strengthen the CBI and broaden its impact.